Occluder

Creates an Occluder derived from an object's position and radius, as well as the camera position. The occluder can be used to determine whether or not other objects are visible or hidden behind the visible horizon defined by the occluder and camera position.

new Cesium.Occluder(occluderBoundingSphere, cameraPosition)
core/Source/Occluder.js 21

Name Type Description
occluderBoundingSphere BoundingSphere The bounding sphere surrounding the occluder.
cameraPosition Cartesian3 The coordinate of the viewer/camera.
Example:
// Construct an occluder one unit away from the origin with a radius of one.
const cameraPosition = Cesium.Cartesian3.ZERO;
const occluderBoundingSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 1);
const occluder = new Cesium.Occluder(occluderBoundingSphere, cameraPosition);

Members

cameraPosition : Cartesian3
core/Source/Occluder.js 68

The position of the camera.

position : Cartesian3
core/Source/Occluder.js 52

The position of the occluder.

radius : number
core/Source/Occluder.js 60

The radius of the occluder.

Methods

static Cesium.Occluder.computeOccludeePoint(occluderBoundingSphere, occludeePosition, positions) → object
core/Source/Occluder.js 380

Computes a point that can be used as the occludee position to the visibility functions. Use a radius of zero for the occludee radius. Typically, a user computes a bounding sphere around an object that is used for visibility; however it is also possible to compute a point that if seen/not seen would also indicate if an object is visible/not visible. This function is better called for objects that do not move relative to the occluder and is large, such as a chunk of terrain. You are better off not calling this and using the object's bounding sphere for objects such as a satellite or ground vehicle.
Name Type Description
occluderBoundingSphere BoundingSphere The bounding sphere surrounding the occluder.
occludeePosition Cartesian3 The point where the occludee (bounding sphere of radius 0) is located.
positions Array.<Cartesian3> List of altitude points on the horizon near the surface of the occluder.
Returns:
An object containing two attributes: occludeePoint and valid which is a boolean value.
Throws:
  • DeveloperError : positions must contain at least one element.
  • DeveloperError : occludeePosition must have a value other than occluderBoundingSphere.center.
Example:
const cameraPosition = new Cesium.Cartesian3(0, 0, 0);
const occluderBoundingSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -8), 2);
const occluder = new Cesium.Occluder(occluderBoundingSphere, cameraPosition);
const positions = [new Cesium.Cartesian3(-0.25, 0, -5.3), new Cesium.Cartesian3(0.25, 0, -5.3)];
const tileOccluderSphere = Cesium.BoundingSphere.fromPoints(positions);
const occludeePosition = tileOccluderSphere.center;
const occludeePt = Cesium.Occluder.computeOccludeePoint(occluderBoundingSphere, occludeePosition, positions);

static Cesium.Occluder.computeOccludeePointFromRectangle(rectangle, ellipsoid) → object
core/Source/Occluder.js 481

Computes a point that can be used as the occludee position to the visibility functions from a rectangle.
Name Type Default Description
rectangle Rectangle The rectangle used to create a bounding sphere.
ellipsoid Ellipsoid Ellipsoid.default optional The ellipsoid used to determine positions of the rectangle.
Returns:
An object containing two attributes: occludeePoint and valid which is a boolean value.

static Cesium.Occluder.fromBoundingSphere(occluderBoundingSphere, cameraPosition, result) → Occluder
core/Source/Occluder.js 129

Creates an occluder from a bounding sphere and the camera position.
Name Type Description
occluderBoundingSphere BoundingSphere The bounding sphere surrounding the occluder.
cameraPosition Cartesian3 The coordinate of the viewer/camera.
result Occluder optional The object onto which to store the result.
Returns:
The occluder derived from an object's position and radius, as well as the camera position.

computeVisibility(occludeeBS) → Visibility
core/Source/Occluder.js 280

Determine to what extent an occludee is visible (not visible, partially visible, or fully visible).
Name Type Description
occludeeBS BoundingSphere The bounding sphere of the occludee.
Returns:
Visibility.NONE if the occludee is not visible, Visibility.PARTIAL if the occludee is partially visible, or Visibility.FULL if the occludee is fully visible.
Example:
const sphere1 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1.5), 0.5);
const sphere2 = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -2.5), 0.5);
const cameraPosition = new Cesium.Cartesian3(0, 0, 0);
const occluder = new Cesium.Occluder(sphere1, cameraPosition);
occluder.computeVisibility(sphere2); //returns Visibility.NONE

isBoundingSphereVisible(occludee) → boolean
core/Source/Occluder.js 201

Determines whether or not a sphere, the occludee, is hidden from view by the occluder.
Name Type Description
occludee BoundingSphere The bounding sphere surrounding the occludee object.
Returns:
true if the occludee is visible; otherwise false.
Example:
const cameraPosition = new Cesium.Cartesian3(0, 0, 0);
const littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
const occluder = new Cesium.Occluder(littleSphere, cameraPosition);
const bigSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -3), 1);
occluder.isBoundingSphereVisible(bigSphere); //returns true
See:

isPointVisible(occludee) → boolean
core/Source/Occluder.js 167

Determines whether or not a point, the occludee, is hidden from view by the occluder.
Name Type Description
occludee Cartesian3 The point surrounding the occludee object.
Returns:
true if the occludee is visible; otherwise false.
Example:
const cameraPosition = new Cesium.Cartesian3(0, 0, 0);
const littleSphere = new Cesium.BoundingSphere(new Cesium.Cartesian3(0, 0, -1), 0.25);
const occluder = new Cesium.Occluder(littleSphere, cameraPosition);
const point = new Cesium.Cartesian3(0, 0, -3);
occluder.isPointVisible(point); //returns true
See:
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